<li>it is of type "normal" and contains a <body> element.</li>
<li>it contains payload elements typically used in IM (&xep0184;, &xep0085;).</li>
<li>it is of type "error" and it was sent in response to a &MESSAGE; that was eligible for carbons delivery (Note that as this would require message tracking and correlation on the server, it is unlikely to be generally appropriate for most implementations).</li>
<li>it contains payload elements typically used in IM (&xep0184;, &xep0085;, &xep0333;).</li>
<li>it is of type "error" and it was sent in response to a &MESSAGE; that was eligible for carbons delivery.</li>
<li>it matches the MUC-related rules outlined below.</li>
</ul>
<p>To properly handle messages exchanged with a MUC (or similar service), the server must be able to identify MUC-related messages. This can be accomplished by tracking the clients' presence in MUCs, or by checking for the <tt><x xmlns="http://jabber.org/protocol/muc#user"></tt> element in messages. The following rules apply to MUC-related messages:
Georg Lukas
4 years ago